Recent studies by the World Health Organization indicate that as many as one billion people lack access to a source of improved drinking water. Consequently, more than two million people die per year of waterborne disease, and more still are afflicted with non-fatal waterborne diseases. Most of these people live in developing countries, refugee camps, or disaster relief shelters, where conventional water treatment systems may be cost-prohibitive (or the resources required to power such systems—e.g., electricity, fuel, etc.—may not be readily available).
Conventional approaches to electricity-less water disinfection include of ultraviolet (UV) germicidal irradiation, which typically uses a mercury vapor lamp to deliver germicidal UV radiation. Although such systems compare favorably with other water disinfection systems, they also introduce environmental hazards that other systems do not. For instance, a full-spectrum mercury vapor lamp will produce ozone at certain wavelengths. Moreover, exposure to germicidal wavelengths of UV radiation can be harmful to humans (e.g., resulting in sunburn, skin cancer, or vision impairment).